Transmission rates of cable modems based on the DOCSIS3.0 standard has been substantial increased. Furthermore, downstream data transmission band of downstream path has extended from 860 MHz to a 1002 MH. The transmission band is close to Multimedia over Coax Alliance (MoCA), often causing downstream data to be interfered by the MoCA signal. A traditional method of filtering interference signals from the MoCA signal is applied in a LC filter. However, because the frequency band of the downstream path is too close to the frequency band of the MoCA signal and because the filter ability of the LC filter is limited, this results in the interference signal from the MoCA signal not being effectively filtered. Special high-frequency portions of the cable modem downstream data (near 1002 MHz) are still susceptible to interfering MoCA signals, which may lead to an increased data transmission error rate, and may reduces the transmission rate and receiver sensitivity of the cable modem.